JPS6336553Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is designed to elastically clamp and fix the end of the tape between the reel hub and the clamp member when winding the tape around the reel housed in the cassette case. The present invention relates to a tape cassette constructed as shown in FIG.

FIG. 1 is an overall view of the tape cassette, in which 5 is a cassette case, 6 is a reel rotatably supported in the cassette case 5, and 1 is a tape cassette.
is the tape wound on the reel 6.

FIG. 2 shows the structure of a conventional tape reel 6 in a tape cassette configured as described above. In the same figure, 2 is a reel hub, and this reel hub 2
A groove 2a is formed in a part of the outer periphery of the groove 2a, and at the deepest part of the groove 2a, locking parts 2b and 2 are recessed in the circumferential direction at both ends of the groove 2a in the circumferential direction.
b is formed. Reference numeral 3 designates a clamp member, and this clamp member 3 is made of an elastic body and is formed into a partial cylindrical shape with a constant wall thickness, and at both ends in the circumferential direction are both locking portions 2b of the reel hub 2,
Leg portions 3b, 3b that fit into the leg portion 2b are integrally connected. A tape reel 6 is constituted by such a clamp member 3 and the reel hub 2.

In the tape cassette having the above structure, the clamp member 3 is deformed with fingers or the like so that the curvature of its curved surface becomes larger, and then formed on the reel hub 2 together with the end portion of the tape 1 that is brought into contact with the inner curved surface side. By pushing it into the groove 2a from the outside and releasing the deforming force caused by fingers, etc.,
This clamp member 3 is elastically fitted into the groove 2a. At this time, the legs 3b, 3b on the side of the clamp member 3 are fitted into the locking parts 2b, 2b of the groove 2a in a manner that prevents them from coming off, and thereby the end portion of the tape 1 is held against the spring of the clamp member 3. By force,
This clamp member 3 and the groove 2 of the reel hub 2
The reel 6 is clamped between the reel 6 and the reel 6.

According to the conventional tape cassette constructed as described above, since the wall thickness of the clamp member is constant in the circumferential direction, when the wall thickness is reduced, the curvature of the curved surface of the clamp member becomes large (curvature The force that opposes the deformation force generated by the stress distribution when the tape is deformed so that the radius becomes smaller (i.e., the spring force that clamps the end portion of the tape) is small, for example, when the tape stops in rapid forward motion. The ends of the tape may come off unexpectedly due to the impactful tensile force that is applied to the tape.
Alternatively, there were drawbacks such as the clamping point moving.

Additionally, if the wall thickness is increased, the spring will increase due to stress distribution, but when the clamp member is deformed so that the curvature of its curved surface increases, the relationship between the legs and both circumferential ends of the clamp member increases. The disadvantage was that compressive stress concentrated at the joints, causing breakage.

The spring force and breaking strength of the conventional clamp member described above will be described in detail later in comparison with the spring force and breaking strength of the clamp member of this invention.

This idea was made to solve the above problems, and by a simple structural improvement such as providing a roughly semicircular protrusion on the clamp member,
It is an object of the present invention to provide a tape cassette that can increase spring force while ensuring sufficient breaking strength.

An embodiment of this invention will be described below based on the drawings.

FIG. 3 shows the structure of a tape reel of a tape cassette according to an embodiment of this invention. In the figure, 1, 2, and 6 are the same as the conventional example shown in FIG. Therefore, their explanation will be omitted. In FIG. 3, reference numeral 3 denotes a clamp member, and the structure of this clamp member 3 differs from that of the conventional example shown in FIG. 2 in the following points.

That is, FIGS. 4A and 4B are an enlarged plan view and side view showing the clamp member 3 of the tape cassette according to an embodiment of the invention, and in the same figures,
3a, 3a are substantially semicircular protrusions, and these two protrusions 3a, 3a are the inner curved surfaces of the clamp member 3, and integrally extend inward from the clamp member 3 on both sides of the central part of its circumferential length. It is prominent.

In the tape cassette constructed as described above, the clamp member 3 is fitted into the groove 2a of the reel hub 2 as shown in FIG. 5 by the same operation as in the conventional example shown in FIG. The end portion of the tape 1 is connected to the concave groove 2a of the reel hub 2 and the clamp member 3.
It is fixed to the clamping reel 6 between the
At this time, due to the presence of the protrusions 3a, the spring force that is contrary to the force that attempts to deform the clamp member 3 so that the curvature of its curved surface becomes larger is increased compared to the one without protrusions, that is, the conventional example. At the same time, damage caused by stress concentration can be suppressed as much as possible.

Below, the comparison results of the spring force between the case where the semicircular protrusions 3a, 3a are provided (corresponding to this invention) and the case where they are not provided (corresponding to the conventional example) will be illustrated.

FIG. 6 is a principal stress diagram of the cross section of the clamp member 3 having no protrusions when the curvature of its curved surface becomes larger, and FIG. These are the principal stress diagrams of the cross section when deformed. In both figures, A is the tensile stress diagram and B is the compressive stress diagram. Each of these diagrams was created based on the results of computer analysis using the finite element method. It is something that

As is clear from the above figures, the clamp member 3
When deformed so that the curvature of its curved surface increases, tensile stress is generated on the outside and compressive stress is generated on the inside, with the center line o of the wall thickness of the clamp member 3 as the boundary, and these two stresses are combined This creates a force that opposes the force F that attempts to increase the curvature of the curved surface, that is, a spring force.

From this point of view, when we observe FIGS. 6A and B and 7A and B, we find that the one in FIG. The stress increases in the X part of the figure, and the compressive stress increases slightly in the Y part of the figure, and the Z part in the figure
Since only a small amount remains inside the semicircular protrusion shown by , the force opposing the above force F is mostly generated by tensile stress. That is, in the case shown in FIG. 7, the compressive strain on the inside of the clamp member 3 decreases, while the tensile strain on the outside increases, and as a result, the strain volume on the outside increases, and S
The compressive stress in the range shown by increases, and the total stress in the range shown by S increases.

As described above, the spring force of the clamp member 3 shown in FIG. 7, which corresponds to this invention, is much larger than the spring force of the clamp member 3 shown in FIG. 6, which corresponds to the conventional example. I understand that it can be fixed with a clamp.

Moreover, FIGS. 8A and 8B are tensile stress diagrams and compressive stress diagrams when the wall thickness of the clamp member 3 shown in FIGS. 6A and 6B is increased. The distribution is almost the same as in Figure 6A, but the stress values increase.

In addition, as shown in Figure B, the compressive stress is concentrated in the area W in the figure and increases in the area S in the figure, so although it is possible to increase the spring force, the cross section V
There is a greater possibility that stress will be concentrated and breakage will occur. On the other hand, in the case shown in FIG. 7, although the compressive stress in the range shown by S increases and the spring force increases, there is no stress concentration at the cross section V, and the semicircular protrusions 3a, 3a It can be seen that the presence of this can suppress the destruction of the clamp member 3 as much as possible.

In the above embodiment, the case where the present invention is applied to a clamp member of a video tape cassette has been described, but the present invention may be applied to a clamp member of any other device using magnetic tape.

As described above, according to this invention, the spring force of this clamp member can be increased by simply making a structural improvement such as arranging approximately semicircular protrusions on the inner curved surface of the clamp member. This has the effect of being able to strongly clamp and fix the clamp member, and increasing the breaking strength of the clamp member itself.

[Brief explanation of the drawing]

Figure 1 is a front view showing the entire tape cassette;
FIG. 2 is a perspective view showing the structure of a tape reel in a conventional tape cassette, FIG. 3 is a perspective view showing the structure of a tape reel in a tape cassette according to an embodiment of the invention, and FIGS. 4A and B are clamp members. FIG. 5 is an enlarged plan view of a partially broken tape reel, FIGS. 6A and B are principal stress diagrams of the conventional clamp member, and FIGS. 7A and B are the clamp member of this invention. FIGS. 8A and 8B are principal stress diagrams when the wall thickness of the conventional clamp member is increased. DESCRIPTION OF SYMBOLS 1... Tape, 2... Reel hub, 2a... Concave groove, 2b... Locking part, 3... Clamp member, 3a
...Semicircular protrusion, 3b...leg, 5...cassette case, 6...reel. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] The reel that is housed in the cassette case and winds the tape is connected to the reel hub, which has a groove formed on a part of the outer periphery of the boss part, and the reel hub, which is made of an elastic material and has a cylindrical part with a constant wall thickness, and has an elastic part formed in the groove. A clamp member that can be fitted into the groove is formed with a locking portion that is recessed in the circumferential direction at the deepest part of the groove and at both ends of the groove in the circumferential direction. In the tape cassette, leg portions are formed at both ends in the circumferential direction to fit into the locking portions, and the ends of the tape are held between the clamp member and the groove of the reel hub. A tape cassette characterized in that approximately semicircular protrusions are protruded inward and integrally provided on both sides of the center point of the circumferential length of the clamp member on the inner curved surface of the member.